This invention relates to an improvement in the method and apparatus for bending sheets of glass disclosed in Application Ser. No. 960,404. In that application an arrangement is disclosed whereby heat-softened glass sheets are lifted by a flat vacuum platen and dropped onto a contoured bending mold so as to shape the glass sheet. Such a system reduces the number of elements which must be custom fabricated for each particular bent glass shape to be produced, thereby reducing the cost and downtime required for each product change. The drop forming technique of the earlier application is also advantageous in that it may readily be adapted to bending and tempering a plurality of glass sheets simultaneously, thereby greatly increasing the productivity of a production line.
While the drop forming method and apparatus of the earlier application are highly advantageous, additional improvements would be desirable. In some cases it may be desired to drop the glass sheets with greater force than provided by gravity in order to produce sharper bends. Also, it may be preferred to increase the speed of the process by accelerating the dropping of the glass sheets onto the shaping mold. A particular need for accelerating the release of the glass sheets from the vacuum platen may arise when the glass sheets tend to stick to the vacuum platen. This may occur, for example, when patterns of frit coating have been applied to the upper surfaces of the glass sheets. Another desirable improvement would be the capability of cooling the vacuum platen so as to maintain a controlled, substantially constant temperature in the bending station.
Applying air to press bending molds for the purpose of cooling has been practiced in the prior art as exemplified by U.S. Pat. No. 3,507,639 (S. L. Seymour) and U.S. Pat. No. 3,529,947 (R. G. Frank).